若log7=a,
问题描述:
若log7=a,
则求log448
答
log7=a,ln7/ln2=a,ln7=aln2
log448=ln448/ln28=(6ln2+ln7)/(2ln2+ln7)
=(6ln2+aln2)/(2ln2+aln2)=(a+6)/(a+2)